crank no start questions m50 engine, need help figuring out where I went wrong

[kar2k]

Hey so I got an m50b20 (VIN: WBACB220X0FA09320), here's a timeline!

I bought the car (sat for 4 years due to transmission sticking in gear issue, no need to keep this info in mind, swapping to manual);

1. Ignition switch was bad (plastic brittle) - replaced that

2. fuel pump was bad - put in a (semi new) pump from an 325i that was sitting for ~7 years. I put in 1.5 gallons of fresh gas, the gas was already low, like had less than reserve of sitting gas.

3. Car started right up, then shut off after like 2-3 seconds. Fuse box area put out a good bit of smoke, i could see the main relay and the fuel pump relay got hot (incidentally I put a marker on them a day before so I noticed the blue ink looked funny). Both Fuse #18, #17 is now giving low voltage, less than 10. Car still had 12v everywhere else, including coil packs.

4. Opened the fuse box and fuse #20 (a/c? i think) was corroded away (but we were jumping the fuel pump #18 fuse from this, so i found this funny). We fixed fuse #20 wiring.

5. Fuse box looks good, nothing looked burnt really. Relay side (main, fuel and the other relay whatever that is) the white plastic is bittle and keeps breaking, but the relays seem to still work. I tried swapping relays around, got a new generic 5pin main relay too incase.

6. Put in a brand new fuel pump from rock auto.

7. We decided to check if it shorted the ECU, turns out the ecu had some water damage.. THOUGH, remember it did start up in one switch with the (semi new but sitting FUEL PUMP).
IMG_8251.jpg

8. took down the carpet from the passenger side under the glove box (left hand side), found a rotted ground, relocated that. It appears water was getting inside everytime rain came, I’m thinking of raising up the carpet and looking for more damage?

9. bought a new ecu, apparently i bought a motronic when the old ecu said dme (i have not opened the new ecu yet). I’m told everywhere there is no difference, but the ignition comes out without messing with the ignition switch (key).. so there seems to be something obviously wrong there
IMG_8220.jpg
10. Mechanic brought a scanner with an ob1 adapter but it said it didn’t detect the ecu (old ecu)
11. Bought a new ECU (one that looks EXACTLY the same as the old one), waiting on it.

NB. The car has started everytime we put gas directly into the intake (shut off right after it starts. Have not tried this since the new ECU).
NB i. We didn't see the coilpacks spark (screwdriver on metal test) with the new ECU on crank, but waiting on the new ECU to properly go through all the main tests again.

All Underlying issues:

1. Ignition Switch - Fixed
2. Fuel pump - Fixed (got a new one)
3. Bad ground under passenger side (connected to ignition module maybe?) - Fixed, relocated
4. Fuse #18 is still not giving 12v unless bridged - Not fixed.
5. No spark from coil pack under crank after all these new issues - Not diagnosed yet
6. Waiting on new ECU and some new relays - In progress

---

Questions:

i. The fuel pump fuse isn't getting 12v, so there is no fuel pump starting on ignition UNLESS you bridge the fuse #18 from another fuse. I'm assuming the wire maybe is damaged else where? I should dig up the carpet and trace the wire right?
ii. The car started (haven't tested it since) when we put gas in the intake, could it start like this if the crankshaft position sensor was bad?
I'm trying to rule out that I have a good fuel pump, ignition switch, CPS?, spark plugs and coils. I can't say if my relays are perfectly working yet.


Yeah so that's what happened, any ideas? ;\

[Eric93se]

Cannot use "generic" relays, they have to be correct, and not just the pin shapes they need to be specific for the car. BMW relays are color coded, you cannot mix t hem up you will burn the harness. You saw smoke, you need to carefully check all the wiring under the relay box and the wire running across the top of the firewall in the engine bay, you have to open up that long box and check all the wires.

If water is getting under the carpet and corroding things then yeah it would be wise to pull up the carpet and fix all of it and find out how water is getting into the car. You should tarp it or garage it when it rains.

There's a good chance your injectors are clogged and or leaking. do not buy new china injectors they are crap and you will only have trouble from them. If you do want this to run good and its running and you want injectors, get the new design bosch injectors, they are a bit taller so you will need slighly longer bolts for the bracket, check rockauto for pics, they have them for the m52 and the m50. You can try rigging something up to flush out your current injectors pressurizing them with a can of cleaner and cycling them with a small 9-12v power supply (small wall wart) and a micro switch to quickly make them squirt (watch youtube).

Your corrodded dme can be cleaned with a can of Deoxit 5% and scrubbed with a toothbrush, it may still work, spray liberally and scrub, repeat, clean both sides of the board as well as the connectors on the outside and the cable side.

When you turn on the ignition you should hear the fuel pump prime, its like 2 seconds. it will not continue to run till the engine runs (crank sensor signal), it does this to prevent flooding. Fixing your injectors is important for the engine to start quickly the first time.

- - - Updated - - -

Get the correct electrical manual for your year/model, they are not the same across models, even the fuse box diagram is different lots of people make t his mistake. At the top of this forum is links to electrical diagrams, the files may be pdf so be sure to take a copy for record.

[kar2k]

IMG_8266.jpgIMG_8265.jpg

1. Alright so in my unprofressional opinion, I caught this water leak just quickly enough to prevent any serious damage. All the wiring looks good. I'll do some rust cleanup, I'm gonna put some electrical tape on the wiring around the top part (under passenger seat). Think I'm just gonna spray some rust-off, get rid of the surface rust, epoxy primer and then green rust check for now. Anyway.
2. I tested 12v to the fuse pump relay, that's good, the connection i.e
3. Just waiting on the ECU now.

2 things:-

Where exactly do I get these 'exact' bmw relays? The thing is i have a 1992 320i m50b20 right hand drive (euro) (So also remember I have no CEL). I've ordered this https://www.rockauto.com/?carcode=1434738&parttype=3380 to use as my main DME relay, should be fine? The old one is white. Fuel pump is blue. And trying to figure out what the other relay next to those are.

That bently service manual link is down. on this link http://wedophones.com/BMWManualsLead.htm the 325i only has the vert manual. I'm assuming I can use a 325i manual but not a vert.

[kar2k]

... ignore this double post

[Eric93se]

As long as you don't put some random relay because it fits in the socket, there is a diagram on the new one which should match the old and do so in diagram but also pin position.

The newer e36's use light blue for the DME and fuel pump.

So while the carpet is up you should do something, I see power distribution 'combs' for at least two groups of positive power. Check them carefully for corrosion. It would be wise to cut the wires off the comb, strip them back an inch, braid them onto one another and solder them together, don't leave any bare wire cover it all with solder and thoroughly electrical tape it up.

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Is that the passenger side?

[kar2k]

- No not random relays, like when I say used a generic relay it’s the correct pinning and correct layout. Don't wanna sound ignorant but how different can they be atleast in an older car like this? Lemme know! IMG_8272.jpgIMG_8277.jpg


My car has a blue 4pin for fuel pump and white 5pin for main dme.
So partsouq is showing me a wrong layout for my car's VIN, showing me the fuel pump has 5 pins etc so for relays I found, I will order these to try with the new DME.

Fuel Pump: https://www.bimmerworld.com/Safety-R...366915327.html (blue 4pin)
Main DME: https://www.bimmerworld.com/BMW-Inte...361729004.html (white 5pin)

- About the combs, you mean these right? IMG_8281.jpeg Never heard that term. I do see corroson on one of them. Thanks for that note.

- Yes it's the passenger side, didn't do the driver side yet since the leak is on the passenger side and most of the wiring (and fuel pump wiring) is on the passenger side (remember right hand drive).

- I think I'm gonna follow this post https://www.bimmerforums.com/forum/s...6#post28879546 and report back those results here in the day.

[Eric93se]

So that black relay seems like it should work, personally I would only buy correct color coded ones.

I would solder the wires for all of those combs. On my left hand drive I don't have the comb with the large red wires. Wonder if they are under the right side.

[kar2k]

Yup, so I got a new ECU and new main relay today. Put them in, put on the battery, all works as it should, but still no start.

Definitely have a wiring issue, not hearing the pump, but the pump is good when it gets direct 12v, fuel pump relay connections have 12v.

Meh, might just buy a whole engine harness.


Gonna try and diagnosing the issue more. Whatever caused the smoke around the fuse box area has to be the issue. Because technically the harness should be good, since it worked properly before that, so rat definitely didn't bite anything imo.

[kar2k]

Okay so big update:

Pre Stance:

7v to the fuel pump
Brand new URO fuel pump stuck

Now:

Gas had this slimey feeling, assuming that’s what got the new fuel pump stuck. Put in 2 bottles of marvel mystery oil and about 1.25 gallons of gas.
Got a fuel pump from a 6 cylinder altezza (is200) and installed that on the bmw housing.
Took off the back seat and cleaned the ground that’s connected to the tail light wiring and fuel pump, now getting 12v lol.
Car now starts sometimes while cranking, leaving the car for awhile then cranking commences an immediate start, but the are also immediately stalls.
Car wants to start most times, we have 12v to the injectors and we have spark.

Future:

- We are assuming we need new fuel injectors, probably clogged from that old gas? Cranking sometimes it sounds start-ish so it kinda sounds like some the injectors spit sometimes they don't.
- Oil in engine is very low, does the e36 platform have a sensor to shut off the engine on low oil?
- Gonna buy injectors off rock-auto (13641730059 is the part number off partsouq)

[Eric93se]

That injector part number looks correct but in the future use realoem for OEM diagrams and part numbers. Select classic catalog and used either your VIN or month/year from the b-pillar. Change you fuel filter too.

[Eric93se]

Does the Bosch 62415 model fit your car? It would be an upgrade over the stock design as long as its a direct fit and the correct flow rate. That design is available for the m50 and m52 (both with correct flow rates) they are a bit taller and need a longer hold down screw.

[kar2k]

Does the Bosch 62415 model fit your car? It would be an upgrade over the stock design as long as its a direct fit and the correct flow rate. That design is available for the m50 and m52 (both with correct flow rates) they are a bit taller and need a longer hold down screw.

Dunno, Looks like realoem has the same part number as partsouq, https://www.realoem.com/bmw/enUS/par...&q=13641730059

Might it? I'm gonna get them cleaned for now and order some new ones, I'd love an upgrade.

Here is a video of how it sounds, confirmed most spark plugs are dry.

https://i.imgur.com/N82Ewrd.mp4

[kar2k]

Yeah we did it! I got the injectors cleaned and #2 was blocked, #4, 5 and 6 we're dead but they got kicked back into some life!

So i'm gonna look for some injectors to put in my cart for now but it's alive!

Thermostat housing seems cracked and blocked so slowly overheating. And there sounds like a vaccum leak, trying to find that.

Otherwise it's all good!

[Eric93se]

Well you can try putting two bottles of injector cleaner and some more premium gas.

[kar2k]

Actually yeah I put 2 bottles of marvel mystery oil in the old gas LOL before adding more gas, I gotta add more gas tomorrow to balance it out.
Also where I’m from we only have 1 type of gas (unleaded) they don't disclose the octane with us, shell (sol) and rubis. I think rubis is 89 and sol is 91. Very stupid.

I'm gonna buy some parts from bimmerworld, a lower celcuis thermostat, just for the woes cus i'll be having fun (71 c), aluminum housing, new gasket, silicone hoses for now. I'll do waterpump, etc later on. The intake boot AFTER the maf might have some cracks in it, so i'm ordering that. That could be an issue too.

Noticed like 1/10 times my fuel guage works, gotta diagnose that next also.

Here's a video of how it sounds! https://i.imgur.com/sF100HT.mp4

New MANN oil filter is coming on like tuesday, I got castrol gtx 10w-30 to put in.

[kar2k]

Alright update, sadly it's not finished.

I removed the thermostat for now and put in a used housing from an old car. Still haven't received my new stuff from ecstuning and fcpeuro (it takes longer due to where I live).

I took a drive to a gas station (transmission is horrible af, still waiting on my gearbox swap kit), it blew out ALOT of smoke but eventually it stopped, just throwing rich smelling fumes now.

The car was running alright, it had a surging idle, sounded pretty good sometimes, but 95% of the time the idle was surging, changed the oil, with a new filter and seals.

So on Sunday it started missing, then it started to not start properly, it would just choke choke choke now it's not starting at all. I just tried to put 3 gallons in the tank because everyone here agrees it was running super rich, and nothing! just cranks. (fuel pump etc is all still good, fuel pressure is crazy good)

Pulled the spark plugs, they are WET, we played around with #1 and #2 and one time #1 didn't fire but it fired pretty much all the other times, weird stuff.

I ordered new spark plugs.

I'm assuming the injectors are messed up again, I really need suggestions for this, I can't purchase brand new genuine ones, too expensive for 6 lol. I just tried to put some gas in the intake but that didn't work so that’s a hmm from me but I do think I didn't do it properly.

So yeah, weird stuff, need fuel injector suggestions.